Chimney cowls and ventilating devices



July 31, 1962 C. E. BREWER CHIMNEY COWLS AND VENTILATING DEVICES Filed March 27, 1959 INVENTOE. C/i/fard fdmund Brewer M .45am

United States Patent Ofifice 3,h4h,8fi7 Patented July 31, 1962 3,046,867 CHIMNEY COWLS AND VENTILATING DEVICES Clifiord Edmund Brewer, Lucky Stars, Lagoon Road, Lippiput, Parkstone, Dorset, England Filed Mar. 27, 1959, Ser. No. 802,374 Clanns priority, application Great Britain Apr. 1, 1958 5 Ciaims. (Cl. 9882) The present invention relates to chimney cowls and ventilating devices of the type which includes a vertical portion adapted to be located in coaxial relationship with respect to the chimney and situated above and normally outside the diameter of the chimney to form a cowling shaped to create a reduced pressure in the flue 'or air duct.

For the purpose of describing and claiming this invention the type of ventilating device will be referred to as a cowl.

In the known forms of cowls the reduction of pressure in the flue or air duct is effected either by having an annular space at the bottom of the cowl and surrounding the outer periphery of the chimney which produces an upward current of air to draw the flue gases out of the flue or air duct or the cowl is provided with a series of vertically arranged openings by which by the passage of air through or past them an increased upward draught in the fine is obtained.

It has been found that with this latter type of cowl any wind blowing across the chimney top tends to blow into the cowl at the same level to be diverted down the chimney to produce a down draught rather than the desired up draught.

According to the present invention a cowl of the type referred to includes a central upstanding portion adapted when in position to be coaxially arranged with the chimney top and spaced inwardly from the outer vertical portion and extending from the top of the chimney to a substantial distance upwardly into the body of the cowl. Any draught entering from the outside of the cowl is deflected around the upstanding portion and is directed upwardly to produce the desired result of an increased up draught in the chimney. in a preferred form of the invention this is encouraged by making the lower end of the cowl open at the bottom so that convection currents enter through the bottom of the cowl to rise in the cowl to leave it at its upper portion. Furthermore an increased draught is also encouraged by the fact that the actual length of chimney is slightly increased.

The central member which extends from the top of the chimney can be of any suitable cross section and whilst it may comprise simply a cylindrical member of the same diameter as the chimney and having its lower edge abutting npon the chimney lip, it may also be of any other configuration for example conforming with or contrasting with the configuration of the cowl. In this case and where the central member does not conform to the shape of the chimney there is conveniently arranged around the base of that member a member adapted to surround the chimney top and effectively closing any gaps existing between the chimney top and the central member.

Conveniently the cowl may incorporate the inventions the subject of the complete specifications of my co-pending applications Numbers 758,537 filed September 2, 1958 and 758,490 filed September 2, 1958, now Patent 2,988,982 and in these cases the upstanding central member may simply comprise extensions of the interengaging arcuate members forming the means for fastening the cowl to the chimney. In that these members are adjustable to the diameter of the chimney the upstanding member will also be of the same diameter as the diameter of the chimney whatever the size of chimney.

The invention will now be described with reference to the accompanying drawings in which:

FIGURE 1 shows a breakaway drawing of a cowl constructed in accordance with the present invention secure to a chimney;

FIGURE 2 shows an underneath plan view of the cowl shown in FIGURE 1 and FIGURE 3 shows an alternative shape of central structure of the cowl.

Referring to FIGURE 1 the cowl comprises four vertically arranged dish shaped members 1 arranged to form an outer cowl of familiar shape. The top of the members 1 is closed in by means of a cover piece 2 which is dish shaped to encourage gases collecting in the cowl to leave by the vertical open spaces formed between the dished members 1.

The lower ends of the dish member-s1 are connected b connecting pieces 3 which span the lower end of the gap forming the vertical air ducts between the members 1.

Centrally disposed inside and extending from the lower end of the cowl is a central tubular structure 4 which is made up of an expansible structure in accordance with the construction described in the complete specifications of co-pend-ing applications Numbers 758,537 and 758,490. The structure 4 in accordance with the aforesaid applications comprises a plurality of interengaging members 5 and 6 which are in sliding engagement with each other so that they may be closed or opened to vary the cross sectional area. This is achieved by means of screws 7 mounted for rotation in the dish shaped members 1 and in threaded engagement with the members 5 and 6 so that by rotating the screws 7 the members can be expanded or contracted to engage frictionally with the inside of the chimney 8 as shown in FIGURE 1. Alternatively to the screw members 7 engaging in the members 1 they may engage in the connecting pieces 3 in similar manner.

In accordance with the present invention the members 5 and 6 are extended so as to project upwardly fora substantial distance into the inside of the cowl to form the central upstanding portion.

FIGURE 3 shows a central upstanding portion which is square in shape to fit chimneys having a square cross section internally. In this case the members 5 and 6 are of angled section and the screws 7 engage the members 5 in the corner of the angle so that by screwing the screws 7 the members 5 and 6 slide with respect to each other to produce the required size rectangle. The square structure shown in FIGURE 3 can be inserted into the same shape outer cowl as can a circular central structure and the square structure shown in FIGURE 3 can in fact be substituted for the circular structure 4- shown in FIGURES 1 and 2.

The lower end of the cowl is not closed in so that there is formed at the bottom of the cowl and between the members 1 and the structure 4 an open annulus through which upwardly rising air can pass to create an up draught in the cowl and hence in the chimney.

The cowl can be made of any suitable material and conveniently can be made from sheet metal produced from simple pressing operations the component parts being readily assembled by welding or rivetting.

What :I claim is:

1. A cowl for a chimney, comprising an outer hollow body having upstanding side walls, a top wall closing the upper end of the body, and lengthwise extending apertures in said side walls, a central tubular structure having an expansible peripheral wall extending co-axially a substantial distance into the body in spaced relation therewith, a portion of said tubular structure extending downwardly from the lower end of the body for engagement in a chimney, means accessible from outside the body for expanding or contracting the peripheral wall of the tubular structure to obtain a close fit between the downwardly extending portion of the tubular structure and the chimney, the said means further providing a sole means sup 7 porting the body on the tubular structure.

2. A cowl as claimed in claim 1 in which the side walls of the body comprise a plurality of externally concave members secured together with their respective adjacent vertical edges in spaced relation to form said lengthwise extending apertures; the said peripheral wall of the tubular structure comprising wall vportions slidably engaged one with another for expanding or contracting the said peripheral wall; and thesaid supporting means comprises screw threaded elements rotatably. mounted in the said concave members and threadingly engaging respective wall portions of the tubular structure for efl ecting said relative sliding of said wall portions. 7

3. A cowl as claimed in claim 1 in which the top'wall of the body is dished.

4. A cowl as claimed in claim I wherein the central tubular structure is of circular section.

5. A cowl as claimed in claim 1 wherein the central tubular structure is rectangular in sect-ion.

References Cited in the file of this patent UNITED STATES PATENTS 

